Vacuum-type circuit interrupter with flexible, weld-breaking contact structure

ABSTRACT

A contact member for a vacuum-type circuit interrupter having a ring-shaped electrode joined to the contact member adjacent its outer periphery and a movable conductive support rod extending from the center of the contact member for moving the electrode into and out of engagement with another contact member. The positioning of the electrode adjacent the periphery of the contact member allows the utilization of the maximum available lever arm to apply a breaking force on welds occurring between the electrode and the other contact member. The contact member may be slightly deformable to allow application of a prying action to the welded electrode.

United States Patent 13,591,743

[72] Inventor John W. Ranheim 3,366,762 1/1968 Smith Jr. 200/144(1) Oak Creek, Wis. 3,372,258 3/1968 Porter 200/144 (.2) PP 7751428 FOREIGN PATENTS f 133 3 1,113,837 5/1968 GreatBritain 200/144 .2 6,503,070 3 1965 N th la d 200 144 .2 [73] Assignee MtGrlw-Edison Company e er n S l El i 1", Primary Examiner- Robert K. Schaefer Assistant Examiner- Robert A. Vanderhye Attorney-Richard C. Ruppin [54] VACUUM-TYPE CIRCUIT [NTERRUPTER WITH FLEXIBLE, WELD-BREAKING CONTACT I STRUCTURE ABSTRACT: A contact member for a vacuum-type circuit in- 7 Cl i 4 D i Fi terrupter having a ring-shaped electrode joined to the contact member adjacent its outer periphery and a movable conduc- [52] U.S.Cl HMO/$1372: five support rod extending from the center of the Contact [51] lnt.Cl 01h member for movinghe electrodeimo and outofengagemem g with another contact member. The positioning of the elec- [50] Field of Search 2 0/1 ode adjacent the periphery ofthe Contact member allows the 33213221032331 fil oi'iui ifig filfwif 11113623355 Z13 UNITED STTES PATENTS the other contact member. The contact member may be 3,280,286 10/1966 Ranherm 200/144 (.2) slightly d f bl to allow appfication f prying action m 3,3 19, l Lee the welded electrode lea PATENTED JUL 6 |97| FIGZ INVENTOR FIGI ATTORNEY BACKGROUND OF THE INVENTION Vacuum circuit interrupters generally include an evacuated insulating housing and circuit making and breaking contact members constructed to move into and out of engagement. When the contact members move into and out of engagement, an arc is initiated between their electrode surfaces which heats the electrode surfaces to a relatively high temperature. The heating of the electrodes results in the melting of the metallic contact material of which they are comprised so that a weld may be fonned between the electrode surfaces upon cooling of the liquid contact material after the contacts are brought into high-pressure engagement. Such welds are objectionable primarily because they interfere with the proper and easy disengagement of the contacts to open the circuit in which the contacts are connected.

Prior art methods for avoiding objectionable contact welds include the use of electrode contact material in which weld forming is minimized or which form relatively low-strength welds which can be easily broken upon disengagement of the contact members. However, such contact materials typically present problems such as poor electrical conductivity or low thermal conductivity resulting in poor are interrupting qualities.

Another well-known method for rapidly extinguishing the are between the contacts and avoiding welding is to provide a construction in which there is a magnetic force on the arc which moves it to the periphery of the contact member where it is extinguished. Although this method does cause rapid movement of the arc and minimized welding to some extent, welds which must be broken upon disengagement of the contact members nevertheless continue to occur.

SUMMARY OF THE INVENTION It is an object of the invention to provide a new and improved contact for a vacuum-type circuit interrupter.

Another object of the invention is to provide in a vacuumtype circuit interrupter a contact having improved weld breaking qualities.

Another object of the invention is to provide a contact for a vacuum-type circuit interrupter constructed to allow application of maximum breaking force to any weld forming on the contact.

Another object of the invention is to provide a contact for a vacuum-type circuit interrupter constructed to allow application of a prying force to break any weld forming on the contact.

A further object of the invention is to provide in a vacuumtype circuit interrupter contact means having a large contact surface area upon which an arc may move whereby melting of contact surface material is minimized.

In general terms the invention comprises a contact member for vacuum-type circuit interrupters having a movable conductive support rod for moving the contact member into and out of engagement with another contact member. The contact member has an electrode for engaging the other contact member positioned at a distance from the conductive support rod such that substantially the maximum available lever arm is utilized in breaking any weld occurring between the electrode and the other contact member upon disengaging movement of the support rod. The contact member may be formed from flexible material so that it deforms slightly and subjects the welded electrode to a prying action.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view, partly in section, of a vacuum circuit interrupter illustrating two contact members constructed according to the instant invention;

FIG. 2 is a sectional view taken along lines 2-2 of FIG. 1;

FIG. 3 is a top view of the lower contact member shown in FIG. 1; and

FIG. 4 shows the contact members of FIG. 1 during disengaging movement prior to breaking of a weld.

DESCRIPTION OF THE PREFERRED EMBODIMENT FIG. 1 shows a vacuum-type circuit interrupter 2 having a vacuum chamber 10 including open ended housing portions 4 and 5 composed of any suitable electrical insulating material, such as ceramic. The housing portions 4 and 5 are connected by a bulbous arcing chamber 7 and upper and lower end caps 6 and 8 are respectively fixably secured to the other open ends of each of the housing portions 4 and 5. A fixed contact member 12 and a movable contact member 14 are axially aligned within the envelope 10. The fixed contact member 12 includes a conductive support rod 16 sealed to the upper end cap 6 and extending downwardly therefrom, a disc-shaped conductive member 18 integrally joined to the conductive support rod 16 and a frustoconical support member 20 connected between the support rod 16 and the disc-shaped member 18. The movable contact member 14 includes the disc-shaped conductive member 22 positioned opposite the disc 18, a conductive support rod 24 and the frustoconical support member 26. The conductive support rod 24 extends through the aperture 30 in the end cap 8 and is movable along its axis to move the movable contact member 14 into and out of engagement with the fixed contact member 12 by means which are not shown but which are well known in the art. A bellows 28 or its equivalent structure, is connected in a vacuum-tight relation at each of its opposite ends to the support rod 24 and to the lower end cap 8 in surrounding relation to the aperture 30.

An arc chamber liner 32 is affixed to the arcing chamber 7 in surrounding relation to the disc-shaped members 18 and 22 to prevent contact material, which may be vaporized during an arc interruption, from depositing on the inner surface of the arcing chamber 7 and thereby provide a short circuit path around the contact members 12 and 14. In addition, generally cup-shaped shields 54 and 56 are affixed to the support rods 16 and 24 for electrostatically shielding the joints between the end caps 6 and 8 and their associated housing portions 4 and 5 With reference to FIGS. 2 and 3, the disc-shaped member 18 has slots 34 formed therein and an electrode ring 36 joined thereto. The disc-shaped member 22 has slots 38 formed therein and an electrode ring 40 joined thereto. The rings 36 and 40 may be joined to their associated discs by any suitable manner resulting in a firm electrical and mechanical connection, such as brazing. As may be seen in FIGS. 2 and 3, the arcuate slots 38 are spaced apart and extend spirally in an outward direction from a position adjacent the support rod 24. The slots 38 terminate within the outer periphery of discshaped member 22 prior to their intersection with the inner circumference of the ring-shaped electrode 40. It should be understood, however, that the slots 38 may terminate at any point within the disc 22 or may extend out to and open at the outer periphery of the disc 22. At their outer point of termination, the slots 38 are generally tangential to the outer periphery of disc-shaped member 22 and electrode ring 40. The slots 34 are positioned similarly in disc-shaped member 18, With reference to FIG. 3, the arcuate slots 38 force the current flowing in the disc-shaped member 22 to follow a generally spiral path as shown by the phantom lines I. This spiral current path in the disc-shaped member 22 provides, in effect, a coil which establishes a magnetic field in a manner well known in the art. Due to the force of the magnetic field, the arc is caused to spin rapidly around the electrode ring 40 and thereby prevent the electrode ring 40 from being heated to excess, as would occur if the arc were to remain stationary.

As previously'discussed. the heat due to arcing on the contacts of vacuum-type interrupters may cause melting of the contact electrode surfaces and consequent welding of the contact surfaces upon high-pressure engagement of the contacts and their cooling. In the construction of the invention, the arc is forced to move onto the electrode rings 36 and 40 so that any heating and welding will occur between the electrode rings 36 and 40. It will be understood, of course, that only one of the contact members 12 and 14 need include the electrode ring of the invention so that arcing and welding will occur between that electrode ring and whatever part of the opposite contact member the electrode ring engages. As shown in FIG. 2, welds such as 42 and 44 will form between the electrodes 36 and 40 or one of the electrodes and the opposite contact. Since the support rods 16 and 24 are positioned at the center of the disc members 18 and 22 and the welds occur on the electrode rings adjacent the outer periphery of the discshaped members 18 and 22 and the welds occur on the electrode rings adjacent the outer periphery of the disc-shaped members 18 and 22, the maximum lever arm obtainable between the electrode rings and welds and the support rods 16 and 24 may be utilized to break the welds upon disengaging movement of the support rod 24.

The contact members 12 and 14 are shown in FIG. 4 during disengaging movement of support rod 24 subsequent to breaking of the weld 44 and prior to breaking of weld 42. The discshaped members 18 and 22 and the support rods 16 and 24 may be formed from relatively flexible conductive material so that they will deform slightly and subject the electrode rings 36 and 40 and the welds 42 and 44 to a prying action. As the contact members 12 and 14 move apart, the discs 18 and 22 deform I slightly and the conductive rods 16 and 24 may deform in the direction of welds such as 42 until they break and the contact members 12 and 14 are completely disengaged. It should be noted that the electrode rings'36 and 40 may be formed from a conductive material such as an alloy of copper-bismuth which forms a low-strength weld and the discshaped members 18 and 22 may be formed from aconductive material such as copper which has high thermal and electrical conductive properties. lt is not intended, of course, that the electrode rings and the disc-shaped members be limited only to the named materials.

As is best shown in F l6. 2, the frustoconical support member 26 has ends 58 and 60 rigidly a ffixed respectively to the conductive support rod 24 and the disc-shaped member 22 between the outer periphery of the disc-shaped member 22 and the end of the support rod 24. The support member 26 serves to support the disc-shaped member 22 and prevent excessive deformation of disc 22. The frustoconical support member 26 is composed of a materialhaving a much lower conductivity than that of the disc-shaped member 22 so that a low impedance path is'notprovided around the slots 38. The frustoconical support member 20 prevents excessive deformation of disc 18 and has ends 62 and 64 attached to the contact member 12.

While only a single embodiment of the invention has been shown herein, it will be realized that many modifications thereof are feasible without departing from the spirit and scope of the invention. It is consequently intended in the appended claims to cover all such variations and modifications as fall within the true spirit and scope of the invention.

What I claim is:

1. In a vacuum circuit interrupter including an evacuated envelope and a pair of contact members constructed and arranged for movement into and out of engagement whereby an arc may be struck between said members resulting in the forming of a weld between the contact members when in an engaged position, the improvement wherein at least one of said contact members comprises:

a disc-shaped member having a first side and a second side facing the other contact member;

an electrode having a ring shape and being integrally joined to the second side of said disc-shaped member adjacent the periphery of the disc-shaped member and contacting the other contact member when said members are in an engaged position whereby any welding together of the contact members occurs on said electrode;

a support rod joined to the disc-shaped member and movable along its axis to move the disc-shaped member into and out of engagement with the other contact member, said support rod extending substantially from the center of the first side of said disc-shaped member in a direction away from the other contact member whereby said weld is readily broken due to the spaced apart positions of the support rod and electrode on said one contact member; and wherein said disc-shaped member is flexible whereby said electrode is subjected to a prying action upon disengaging movement of said support rod.

2. The combination according to claim 1 wherein said discshaped member includes at least one elongate slot formed therethrough and extending around the center thereof from an interior position outwardly toward said ring-shaped electrode and terminating prior to the inner circumference of said ringshaped electrode whereby the current path provided in said disc-shaped member around said slot produces a magnetic field which forces said arc to travel rapidly along said electrode.

3. The combination according to claim 1 wherein said electrode has a flat side facing the other contact member and said flat side contacts the other contact member when said contact members are in an engaged position.

4. The combination according to claim 1 wherein said electrode comprises an electrically conductive material which forms a relatively low strength weld whereby said weld is broken by disengaging movement of the support rod.

5. In a vacuum circuit interrupter including an evacuated envelope and a pair of contact members constructed and arranged for movement into and out of engagement whereby an arc may be struck between said members resulting in the forming of a weld between the contact members when in an engaged position, the improvement wherein at least one of said contact members comprises:

a disc-shaped member having a first side and a second side facing the other contact member;

an electrode having a ring shape and being integrally joined to the second side of said disc-shaped member adjacent the periphery of the disc-shapedmember and contacting the other contact member when said members are in an engaged position whereby any welding together of the contact members occurs on said electrode;

a support rod joined to the disc-shaped member and movable along its axis to move the disc-shaped member into and out of engagement with the other contact member, said support rod extendingsubstantially from the center of the first side of said disc-shaped member in a direction away from the other contact member whereby said weld is readily broken due to the spaced apart positions of the support rod and the electrode on said one contact member; and wherein said disc-shaped member includes at least one elongate slot formed therethrough and extending around the center thereof from an interior position outwardly toward said ring-shaped electrode and terminating prior to the inner circumference of said ring-shaped electrode whereby the current path provided in said disc-shaped member around said slot produces a magnetic field which forces said are to travel rapidly along said electrode. 7

6. In a vacuum interrupter including an evacuated envelope and a pair of contact members constructed and arranged for movement into and out of engagement whereby an arc may be struck between said members resulting in the welding together of the contact members when in an engaged position, the improvement wherein at least one of said contactmembers comprises:

a side facing the other contact member and a support rod extending substantially from the center of said one contact member for moving said one member into and out of engagement with the other member;

at least one elongate slot formed in the one contact member and extending around the center thereof from an interior position outwardly toward and opening at said outer periphery whereby the current path provided in said one contact member around said slot produces a magnetic field which forces said are to .travel rapidly toward said outer periphery;

a ring-shaped electrode joined to said side of said one contact member adjacent the outer periphery of said one member and contacting the other contact member when said members are in an engaged position whereby any welding together of the contact members occurs on said electrode and the weld breaking force upon disengaging movement of the support rod is maximized due to the relative positions of the support rod and electrode on said one contact member; and wherein said one contact member is flexible whereby it deforms to subject any welded portion of the electrode to a prying action upon disengaging movement of the support rod.

7. In a vacuum interrupter including an evacuated envelope and a pair of contact members constructed and arranged for movement into and out of engagement whereby an arc may be struck between said members resulting in the welding together of the contact members when in an engaged position, the improvement wherein at least one of said contact members comprises:

a side facing the other contact member and a support rod extending substantially from the center of said one contact member for moving said one member into and out of engagement with the other member;

a ring-shaped electrode joined to said side of said one contact member adjacent the outer periphery of said one member and contacting the other contact member when said members are in an engaged position whereby any welding together of the contact members occurs on said electrode and the weld breaking force upon disengaging movement of the support rod is maximized due to the relative positions of the support rod and electrode on said one contact member;

at least one elongate slot formed in said contact member and extending around the center thereof from an interior position outwardly toward said periphery and terminating within said periphery whereby the current path provided in said one contact member around said slot produces a magnetic field which forces said are to travel rapidly along said electrode; and wherein said one contact member being flexible whereby said one contact member deforms to subject any weld portion of the electrode to a prying action upon disengaging movement of the support rod. 

1. In a vacuum circuit interrupter including an evacuated envelope and a pair of contact members constructed and arranged for movement into and out of engagement whereby an arc may be struck between said members resulting in the forming of a weld between the contact members when in an engaged position, the improvement wherein at least one of said contact members comprises: a disc-shaped member having a first side and a second side facing the other contact member; an electrode having a ring shape and being integrally joined to the second side of said disc-shaped member adjacent the periphery of the disc-shaped member and contacting the other contact member when said members are in an engaged position whereby any welding together of the contact members occurs on said electrode; a support rod joined to the disc-shaped member and movable along its axis to move the disc-shaped member into and out of engagement with the other contact member, said support rod extending substantially from the center of the first side of said disc-shaped member in a direction away from the other contact member whereby said weld is readily broken due to the spaced apart positions of the support rod and electrode on said one contact member; and wherein said disc-shaped member is flexible whereby said electrode is subjected to a prying action upon disengaging movement of said support rod.
 2. The combination according to claim 1 wherein said disc-shaped member includes at least one elongate slot formed therethrough and extending around the center thereof from an interior position outwardly toward said ring-shaped electrode and terminating prior to the inner circumference of said ring-shaped electrode whereby the current path provided in said disc-shaped member around said slot produces a magnetic field which forces said arc to travel rapidly along said electrode.
 3. The combination according to claim 1 wherein said electrode has a flat side facing the other contact member and said flat side contacts the other contact member when said contact members are in an engaged position.
 4. The combination according to claim 1 wherein said electrode comprises an electrically conductive material which forms a relatively low strength weld whereby said weld is broken by disengaging movement of the support rod.
 5. In a vacuum circuit interrupter including an evacuated envelope and a pair of contact members constructed and arranged for movement into and out of engagement whereby an arc may be struck between said members resulting in the forming of a weld between the contact members when in an engaged position, the improvement wherein at least one of said contact members comprises: a disc-shaped member having a first side and a second side facing the other contact member; an electrode having a ring shape and being integrally joined to the second side of said disc-shaped member adjacent the periphery of the disc-shaped member and contacting the other contact member when said members are in an engaged position whereby any welding together of the contact members occurs on said electrode; a support rod joined to the disc-shaped member and movable along its axis to move the disc-shaped member into and out of engagement with the other contact member, said support rod extending substantially from the center of the first side of said disc-shaped member in a direction away from the other contact member whereby said weld is readily broken due to the spaced apart positions of the support rod and the electrode on said one contact member; and wherein said disc-shaped member includes at least one elongate slot formed therethrough and extending around the center thereof frOm an interior position outwardly toward said ring-shaped electrode and terminating prior to the inner circumference of said ring-shaped electrode whereby the current path provided in said disc-shaped member around said slot produces a magnetic field which forces said arc to travel rapidly along said electrode.
 6. In a vacuum interrupter including an evacuated envelope and a pair of contact members constructed and arranged for movement into and out of engagement whereby an arc may be struck between said members resulting in the welding together of the contact members when in an engaged position, the improvement wherein at least one of said contact members comprises: a side facing the other contact member and a support rod extending substantially from the center of said one contact member for moving said one member into and out of engagement with the other member; at least one elongate slot formed in the one contact member and extending around the center thereof from an interior position outwardly toward and opening at said outer periphery whereby the current path provided in said one contact member around said slot produces a magnetic field which forces said arc to travel rapidly toward said outer periphery; a ring-shaped electrode joined to said side of said one contact member adjacent the outer periphery of said one member and contacting the other contact member when said members are in an engaged position whereby any welding together of the contact members occurs on said electrode and the weld breaking force upon disengaging movement of the support rod is maximized due to the relative positions of the support rod and electrode on said one contact member; and wherein said one contact member is flexible whereby it deforms to subject any welded portion of the electrode to a prying action upon disengaging movement of the support rod.
 7. In a vacuum interrupter including an evacuated envelope and a pair of contact members constructed and arranged for movement into and out of engagement whereby an arc may be struck between said members resulting in the welding together of the contact members when in an engaged position, the improvement wherein at least one of said contact members comprises: a side facing the other contact member and a support rod extending substantially from the center of said one contact member for moving said one member into and out of engagement with the other member; a ring-shaped electrode joined to said side of said one contact member adjacent the outer periphery of said one member and contacting the other contact member when said members are in an engaged position whereby any welding together of the contact members occurs on said electrode and the weld breaking force upon disengaging movement of the support rod is maximized due to the relative positions of the support rod and electrode on said one contact member; at least one elongate slot formed in said contact member and extending around the center thereof from an interior position outwardly toward said periphery and terminating within said periphery whereby the current path provided in said one contact member around said slot produces a magnetic field which forces said arc to travel rapidly along said electrode; and wherein said one contact member being flexible whereby said one contact member deforms to subject any weld portion of the electrode to a prying action upon disengaging movement of the support rod. 